Thermostatic mechanism



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PATENT olf-FICEy SILAS MCCLURE, 0F MINNEAPOLIS, MINNESOTA.

THERMQSTATIC MECHANISM.

Application led January 24, 1923. Serial No. 614,640.

T o all whom it may concern.'

Be it known that I, SILAS MCCLURE, a citizen of the United States, resident of Minneapolis, in the county of Hennepin and State of Minnesota, have invented certain new and useful Improvements in Thermostatic Mechanisms, of which the following is a specification. l

This invention relates to new and useful improvements in thermostatic mechanisms adapted to be positioned within spaces sub-V ject to temperature uctuations and t0 be responsive thereto in order to control or effect movements of other devices such as valves, dampers, switches, etc. It is old in this art to employ a tube xedly secured at one end and containing an elongated rod having a different coefficient of expansion. One end of the rod is usually aixed to one end of the tube While the other rod end freely projects from the tube and' is connected to a lever, lever system, or other' transmission device to carry the power pro` duced by the expansion differential to the place of control. Two striking disadvan` tages of the rigid thermostatic element/s reside in their manifest limitations as to lo cation and effective length. The element must obviously be placed within the com-` partment of which the temperature is to be regulated and hence the element is usually remote from the valve, switch or other con trol to be thermostatically operated. This necessitates the employment of various apparatus for the transmission of the force of the expanded or contracted element with consequent liability to derangement, multiplicity of parts, disgurement of the controlled object and expense.` The effective length of the usual rigid thermostatic element is subject to the dimensional limitations of the compartment. The result is relatively slight movement of the thermo static element for given temperature changes iu turn entailing the necessity for multiplyirgdevers or systems of levers to attain the `desired range of valve movement or throw of a switch. In the art of thermostatically controlling the oven temperature' of gas ranges, these disadvantages are particularly striking. The gas valve must be adjacent the burner to effect most accurate control. rigid thermostatic element must be located in the oven which is remote from the burner manifold. Hence, various transmission ap- Thepliances, multiplying levers, etc., are exteriorly employed at present to permit the small thermostatic movement to act adequately upon the gas valve. These appliances are unwieldly, cumbersome, and disfiguring. They are expensive to manufacture and require a large amount of space in crating and shipment as well as after installation. These many additional parts are themselves subject to unequal expansion and contraction to the detriment 'of accuracy. If the gas valve be` positioned adjacent the rigid thermostat, then'special piping is required to conduct the gas supply to the valve and to conduct the controlled iow to the oven burner.

It is Well-known that the efiiciency and accuracy of control suffers from increase of distance between the control valve and point of use. In short, these present devices may not be positioned with relation to convenience and efficiency but their locations are governed bythe limitations of the rigid thermostatic element. i

This novel thermostatic element is one adapted to function when in a curved or irregular form. i It broadly includes a tube and flexible member of different coefiicients of expansion and will efficiently and accurately function when the tube assumes a path other than straight. This novel type of element may extend from the oven to a valve adjacent an oven burner and its effective length is not confined to that of a single straight line in the oven but may assume a grid-like, convoluted or tortuous path in the oven. Hence, not only may the thermostatically derived force be directly applied at the most convenient and ,efficientA point, but `the amount of desired movement may be directly obtained.

The object therefore of this invention is to provide an improved thermostatic mech-- anism.V

Other objects of the, invention will more fully appear fromthe following description and the accompanying drawings andv will be pointed out in the annexed claims.

In the drawings, there has been disclosed a structure designed tocarry out the objects of the invention but it is to be understood that the invention is not confined to the exact features shown as various changes may be made within the scope of the claims which follow,

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In the drawi s: y

Figure 1 is a view infront elevation of the oven and adjacent portions of a common form of gas range with part of the oven broken away to show the novel thermostaticmechanism;

Figure 2 is a vertical sectional view on the line 2 2 of Figure 1;

.Figure 3 is a cross-sectional view of a center-burner oven to show a different arrangement of the novel mechanism;

Figure 4 is a.' cross-sectional view of a valve with the novel thermostatic element operatively connected;

Figure 5 is an enlarged detail view of a portion of the valve `mechanism shown in Figure 4;

Figure 6 is an enlarged view in side elevation ofthe valve end of the novel element with parts broken away to show the bearing rings and lubricant;

Figure 7 is a view similar to that of Figure 6 but showing the oven end of the novel element; and

Figure 8 is a longitudinally sectional view of the tube to show the coil form of bearing member both in section and in side elevation.

The invention broadly includes a. tubular member and a flexible member having different coefficients of expansion for the same temperature changes. The flexible member is adapted to extend longitudinally within the tubular member preferably with -a running guidin bearin therein and to be fixed at one end t ereto w ile the other end freely projects beyond the tubular member for working connection with the movable part of a valve, switch or other controlling means. Thereis here shown an elongated tube 11 adapted to bear a wire 12. The tube may be of brass which has a relatively high coefficient of expansionwhile the wire may be of steel havino' a relatively low one. However, an alloy o? steel having a relatively low coeiiicient of expansion coupled with 4non-corrosive attributes may be employed. The relation of the inside diameter of the tube to the outside diameter of the Wire is such that the wire, is, at least, provided with a running guiding lit. The wire 12 is flexible in order that the tube may be arcuately curved when installed, both to assure presentation of sufficient length Within an oven and to permit the wire to extend to, and directly contact with, the parts tov be c actuated.

As is shown, in detail in Figures 5 to 8, inclusive, 1t 1s advantageous to insert a bear- ',ing member within the tube by which the a lrunning guiding tit, and out of' contact with the inside face of the tube wall. In-

The relative dimensions of the wire and rings are preferably such as to afford a running guiding fit to the wire and yet not too loose so as to permit buckling of the wire. The coil form of bearing member is shown in 'Figure 8 wherein there is disclosed a coil 14 of suitably dimensioned flexible Wire positioned withinthe tubell. The working wire 12 extends through the convolutions of this coil and likewise is thereby provided with a running guiding fit out of contact with the wall of the tube 11 to avoid frictional resistance to the desired relative movement between tube and working Wire.

A lubricating medium may be placed within the tube 11 as is suggested in Figures 5, 7 andv 8. Such lubricant 15 may be provided by particles of graphite or mica or a mixture of both. The purpose of the lu.- bricant is to minimize any frictional resistance to relative movement of the working wire 12 and the rings or coil, or between the rings themselves or the coil convolutions,

or between either and the inside face of the4 tube wall.

The working wire is fixcdly secured to the tube at one end and freely projects therefrom at its other end. A means of {iX- edly securing one end of the Wire 12 to the tube isshown in Figure Z wherein a terminal portion of the wire 12 is upset to form an enlarged head 16 'to effect a driving fit withthe tube interior. The outer portion of this head is tapered in order to provide space to receive brazing metal 17 by means of which a fixed gas-tight connection of Wire and tube is assured, at this oven end. Thus, any differential of expansion or contraction must be communicated to the free end of the working wire which terminally projects from the other end of the tube and the resultant relative 'm'ovement may be employed to actuate the movable part of a controlling device.

A specific adaptation of this novel thermostatic mechanism is illustrated in the accompanying drawings wherein the wire-containing tube 11 is shown as introduced Within the' oven portion of common forms of gas ranges. In Figures 1 and 2 there are shown portions of aga-s range such as an oven 18 with grid racks 19, dead air jackets 21, circulating flues 23, gas manifold 24, cooking burner mixers and valves 25, oven burner 26 and its mixer 27, all in conformity with modern gas range practice.

By the employment of this novel thermostatic mechanism, the valve for the oven burner may be placed in its most efficient position, i. e., adjacent the oven burner mixer v27. Not only may the valve be efficiently so placed but t-he actuating thermo-element may be extended from its oven position directly to the movable part of the valve.v The efficiency, conveniencev and advantages of such arrangement are indicated in Figures 1 to 3` inclusive. The effective length of the thermostatic element is not limited by any straight line dimension of the oven but may be curved and loosely suspended from a bracket 29 borne by one of the jackets 21. rl`his novel element is also equally useful with the type of center burner shown in Figure 3 wherein the valve is shown at the oven burner mixer 27 while the element curves to one side of the oven and is similarly carried by a bracket 29. Obviously, the element will function equally wellV when shaped into irregular forms or paths other than the substantially circular forms suggested in the drawings.

While other forms of gas valves may thus be thermostatically controlled, there is shown in Figure 4, a specific form of novel valve which forms the subject-matter of another patent application of which the inventor hereof is one of the joint inventors. Generally, this novel valve includes a housing 31 substantially cylindrical in shape and closed at its ends by a front plate 32 and rear plate 33. The `housing has an integral casting 34 having an integral recessed head 35 to receive, in threadedengagement, the end of the gas manifold 24.

The casting 34 is centrally counterboredto form a gas passage from the head to the mixer 27 through the nipple of the casting 34'. A manually operable valve 37 is interposed in this central gas passage so that it may be manually turned to permit gas to flow directly from the inlet portion 38 thereof, through the valve portv 39, to the outlet portion 41 and thence to the burner mixer 27. When so turned, the gas supply can not be thermostatically controlled. This manual valve also has a port 42 which is` shown in Figure 4 as presented to the inlet portion 38 to permit gas to flow to the inlet conduit 43 on one side of the integral web 44'which divides the valve housing into an inlet chamber 45 and outlet chamber 46. An outlet conduit 47 leads from the chamber 46 to the outlet portion 41 of the gas passage to the mixer. A by-pass 48, suitably constricted, is provided to supply suicient for the burner during periods of thermostatic control.

,33 so that this end of'fthe tube may be held in rigid fixed position. The wire 12 freely projects from this valve end of the tube 11 and is adapted to control the operative positions of a valve within the housing 31.

Broadly, this novel valve mechanism includes a sleeve 52 having an intermediate peripheral conoidal valve 53 adapted to coact with the front edge of the central aperture of the web 44. This valved aperture forms the passage for gas between the inlet chamber 45 and the outlet chamber 46. A regulating shaft 54 is received in adjustable threaded engagement and longitudinally extends through the sleeve 52. The rear end of this shaft is enlarged to provide a head having a running guiding fit within the recessed boss 55 forwardly extending from the rear plate 33. This head is provided with a central terminal recess to re- -ceive the end portion of the wire 12.

Means are provided tensionably to hold- As the sleeve is carried in threaded en gagement on the shaft, the sleeve is normally held against rotation so that rotation of the shaft may vary the relative position of the sleeve on the shaft to the end that the valve may be manually set to admit the "passage of a supply of gas suiicient to bring the oven temperature to, and maintain it at, a predetermined degree.

The forward end of the shaft is formed with a transverse slot to receive a tongue 56 terminally projecting within the casing from a plug 57. This plug has a tapered body portion, outwardly diminishing and received for rotative movement within a complementarily shaped aperture in an externally tapered block 58 likewise mounted in a tapered aperture in the front plate 32. The forward' end of the sleeve is provided with opposed tongues 59 received in diametrically alined slots in the annular wall 61 formed by counterboring the rear end of the block. The block 58 is provided with an outwardly terminal stem of irregular cross-Section upon which is mounted the Calibrating disk '62 which is normally held against rotation by the screw 63 mounted in the front plate with the screw-head overhanging aperipheral' portion of the disk. The wall 61 of the block is peripherally threaded for engagement bythe ring-nut 64 gas to the mixer 27 to function as a pilot between the forward face of which and the rear face of the plate 32 is positioned theV coiled compression spring 65 which reacts rearwardly to pull the block in its tapered seat. A compression spring 66 is likewise coiled about the sleeve between the projecting shoulder formed bythe valve 53 and a Washer held by the nut 64. This spring 66 exerts a rearward thrust upon the sleeve to hold the shaft against the wire 12.

The forward end of the plug 57 is provided with a reduced `portion forming a hub 67 having a threaded end portion 69 to receive a nut 68. A compression spring 70 is coiled about the hub and held between the base of a recess in the block 58 and the nut whereby the plug is tensionably thrust forwardly to assure gas-tight seating in its tapered aperture in the block 58. A dial wheel 7l is held to the plug hub by means of the screw 72. The dial wheel, which is graduated to cooperate with a suitable mark on the housing yto indicate corresponding oven temperature-conditions, provides a convenient means for the manual adjustment oi' the regulating shaft4 with relation to the valve-carrying sleeve. The calibrating disk which normally holds the sleeve in nonrotatable position, may be rotatably adjusted to'change a normal operative position of the sleeve with relation to the shaft so that the mechanism may becorrected or calibrated for any inaccuracies in installation ormaintenance.

other application, it need not be described inlgreater detail as this novel thermostatic element is capable of use with various other types of valve meohanimns.

vIn the operation of this mechanism and 4thermostatic element, the dial wheel may be set, as is usual, to indicate the predetermined oven temperature. The resulting shaft movement adjusts the position ofthe lvalve-carrying sleeve to permit a. definite v per'ature rate of flow of Ygas through the valve housing to the oven burner. Asthe oven temapproaches the predetermined degree, the tube and wire are expanded, the rate of expansion of the brass tube being greater than that of the alloy steel wire so that the free end of the wire is drawn to- Iward the tube and fromthe shaft end. The

shaft tensionably follows the wire end with the result that the valve is carried toward its seat to cut downthe gaseous flow. Conversely, y'when the tube and wire are cooled vthey contract, the rate of contraction of the tube being greater than that of the wire. Hence, as the tube and wire are xed together at their oven ends and the wire reely projects from the tube at its fixed valve end, the free4 end of the wire is pushed farther from the `tube and moves the shaft for- .o5 position.

wardly to carry the valve to a more open As this novel valve mechanism forms the subject-matter of an- Having thus described my invention what l claim as new and desire to secure by Letters Patent, is: 1

l. In a thermostatic mechanism, the combination of a tubular member adapted to be shaped into a curved or irregular form, a

flexible element having a different coeicient` of expansion extending longitudinally of and having a running guiding fit within said member, one end of the member and of the element being secured together so that the other portions thereof may have relative movement upontemperature changes, whereby themechanism may thermostatically function when assuming a curvilinear or irregular path.

2. In a thermostatic mechanism, the combination of a tubular member adapted to be shaped into a curved or irregular form, a

flexible element having a different coelicientof expansion extending longitudinally within said member, one end of said member and element being secured together so that the other portions thereof may have relative movement upon temperature changes, and bearing means within said member to provide a running guiding fit for the element,

whereby the` mechanism may thermostatically' function when assuming a curvilinear or irregular path.

3. In a thermostatic mechanism, the combination of a tubular member adapted to be shaped into a curved or irregular form, a

flexible element having a different coefficient of expansion extending longitudinally within said-member, one end of said member and element being secured together so that the other portions `thereof may have relative` movement `upon temperature changes.l and bearing means surrounding said element within saidrmember to provide a running ,guiding bearing for theelement, whereby the mechanism may thermostatically func tion .when assuming a curvilinear or irregular path.

4. In a thermostatic mechanism, the combination of a tubular member adapted to be shaped into a curved or irregular form, a flexible element having a different coefficient of expansion extending longitudinally withinV said member, one end of said member and flexible element having a dierent coeliicientl o expansion extending` longitudinally withiso in said member, one end of said member and element being` secured together so that the other portions thereof may have relative movement upon temperature changes, and an instrumentality coiled about said element within said member to provide runnin guiding bearings for said element where y the mechanism may thermostatically function when assuming a curvilinear or irregular path. y

6. In a thermostatic mechanism, the combination of a tubular member adapted to be shaped into a curved or irregular form, a flexible element having a dierent coeilci'ent of expansion extending longitudinally within and having a running guiding fit Within said member, one end of the member and element being secured together so that the other portions thereof tmay have relative movement upon temperature changes, and lubricating means for said element within said member, whereby the mechanism may thermostatically function when assuming va i curvilinear or irregular path.

shaped into a curved or irregular form, -a

flexible element having` a different coeiicient of expansion extending longitudinally within said member, one end of the member and element being secured together so that the other por-tions thereof may have relative movement upon temperature changes, bearing means for said element within said member to provide a lrunning guiding bearing for the element, and lubricating means for the element-bearing means, whereby the mechanism may thermostatically function when assuming a curvilinear or irregular path.

In witness whereof, I have hereunto set my hand this twentieth day of January SILAS MCCLURE.v 

